Evolution and humans: big brain size or use (Evolution)

DAVID: Exactly the point: If an enlarged brain came first with parts basically unused, because thoughts and activities hadn't been invented as yet, then its plasticity allowed for it to adapt as the mental discoveries advanced.

Pre-humans had brains, and if brains are plastic and conscious demands change them, as shown by the study, it is illogical to argue that the brain changed – whether by enlargement or by complexity - before there were demands.

You are skipping the fact that we have fossil skulls which give us brain sizes which large jumps in volume. We cannot know the brain complexity at each stage, but we can look at stone tools, use of fire, etc. to judge the level of brain use. Of course at each level of size brain plasticity responded to levels of thought and use from developed activities.

DAVID: The gaps in evolution firmly predict change first. use second.

dhw: The gaps cannot “predict” anything. We are trying to explain them, and as you so rightly observed: “This study shows the intimate interconnection of our developing 'self' and how our brain changes to accommodate the integration of experience and responses.” Same again: If our consciousness is independent of our brain (your belief – I remain neutral) and consciousness uses the brain, as you now agree, then the obvious conclusion is that consciousness caused the enlargement, just as it causes the complexifications.

These are not gradual changes in size, 200 cc at a time. And there is no evidence of major advanced uses of the brain until 10,000 years ago as our civilization suddenly advanced, finally taking advantage of our giant brain, which arrived 200,000 years ago.

DAVID: My size first, use second of the brain, still fits what I see as evolutionary history. H sapiens arrived 200,000 years ago with a big jump of 200 cc in brain size. No evidence of new use gradually prodding the plastic brain to change ...etc.

dhw: The “gradualness” of enlargement covers the growth from the earliest hominins to ourselves. If the different stages occurred as big jumps (= saltations), it makes no difference to the argument that the brain changes when consciousness makes new demands. We have already agreed many times that saltations are indeed a mystery and that there is no evidence for my hypothesis or for your own.

Once and for all there is no gradualness, no 'if' about the stages. Yes, saltations, which I think come from God. And not much use until 50,000 years ago with advanced language, and 45,000 years ago with cave art. Not like the use of today, which was allowed 200,000 years ago, but not taken advantage of.

DAVID: Of course a new size implies a causing mechanism. dhw can't find one. I posit God. so we are on opposite sides of his picket fence.

dhw: As usual, you try to shift the argument to belief in God. I am not even discounting the possibility that the size of the brain IS the cause of enhanced consciousness (= materialism). I don’t know the cause of consciousness, whereas you think you do. I am simply pointing out that such a belief is a contradiction of your OWN belief that consciousness/the self (an independent entity which you envisage surviving into an afterlife) uses the brain. Neither belief excludes God anyway, but you are so fixed in your interpretation of his mind that you seem to think any other interpretation is atheistic!

Well at least it is agnostic.

dhw: Thank you for the post that follows, on the subject of language. It is fascinating, but makes not the slightest difference to the argument. You put the following in bold:

DAVID: These mysterious languages demonstrate the brain’s astonishing capacity to decode information from new signals – with insights that are causing some neuroscientists to rethink the fundamental organisation of the brain.

dhw: Nobody will deny the brain’s astonishing capacity to do all sorts of things. But if the brain is a RECEIVER according to your beliefs, it can only have changed when changes were needed in order to decode the information being sent by consciousness.

Thank you. Of the brain's plastic abilities work intimately with consciousness.